In the development process of EU’s financial integration, each member state has its own characterized interior market. Recently, there have been many financial crises in the world, which shows that the financial supervisory system today is still having problem. In order to make this supervisory system more efficient and safer, some principles and rules are needed. Comparing with other EU member states, the Spanish financial market is a flexible one and functions quite well. Its interior market has been through several big reforms, and transformed itself from a closed economy to an opened one, now even integrated into the EU financial system. This thesis takes a viewpoint of state-level to analyze the structure and reforms of Spanish financial system, and also tries to figure out a way to solution. The thesis is divided into 7 chapters and the structure is as follows: chapter 1 is the introduction; chapter 2 is about financial system and financial instrument; chapter 3 is about financial institute and financial market; chapter 4 is about the structure of Spanish financial system and its earlier reforms; chapter 5 is introducing the Bank of Spain and its main functions; chapter 6 is about the financial supervisory cooperation between Spain and EU; and in the end, chapter 7 is the conclusion.